/*
 * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This software has been sponsored by Sophos Astaro <http://www.sophos.com>
 */

#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <stddef.h>	/* for offsetof */
#include <netinet/in.h>

#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <linux/netfilter/nfnetlink.h>

#include <libmnl/libmnl.h>
#include <libnftnl/rule.h>

static void nftnl_mnl_batch_put(char *buf, uint16_t type, uint32_t seq)
{
	struct nlmsghdr *nlh;
	struct nfgenmsg *nfg;

	nlh = mnl_nlmsg_put_header(buf);
	nlh->nlmsg_type = type;
	nlh->nlmsg_flags = NLM_F_REQUEST;
	nlh->nlmsg_seq = seq;

	nfg = mnl_nlmsg_put_extra_header(nlh, sizeof(*nfg));
	nfg->nfgen_family = AF_INET;
	nfg->version = NFNETLINK_V0;
	nfg->res_id = NFNL_SUBSYS_NFTABLES;
}

int main(int argc, char *argv[])
{
	struct mnl_socket *nl;
	char buf[MNL_SOCKET_BUFFER_SIZE];
	struct nlmsghdr *nlh;
	struct mnl_nlmsg_batch *batch;
	uint32_t portid, seq;
	struct nftnl_rule *r = NULL;
	int ret, family;

	if (argc < 4 || argc > 5) {
		fprintf(stderr, "Usage: %s <family> <table> <chain> [<handle>]\n",
			argv[0]);
		exit(EXIT_FAILURE);
	}

	r = nftnl_rule_alloc();
	if (r == NULL) {
		perror("OOM");
		exit(EXIT_FAILURE);
	}

	if (strcmp(argv[1], "ip") == 0)
		family = NFPROTO_IPV4;
	else if (strcmp(argv[1], "ip6") == 0)
		family = NFPROTO_IPV6;
	else if (strcmp(argv[1], "bridge") == 0)
		family = NFPROTO_BRIDGE;
	else if (strcmp(argv[1], "arp") == 0)
		family = NFPROTO_ARP;
	else {
		fprintf(stderr, "Unknown family: ip, ip6, bridge, arp\n");
		exit(EXIT_FAILURE);
	}

	seq = time(NULL);
	nftnl_rule_attr_set(r, NFTNL_RULE_ATTR_TABLE, argv[2]);
	nftnl_rule_attr_set(r, NFTNL_RULE_ATTR_CHAIN, argv[3]);

	/* If no handle is specified, delete all rules in the chain */
	if (argc == 5)
		nftnl_rule_attr_set_u64(r, NFTNL_RULE_ATTR_HANDLE, atoi(argv[4]));

	batch = mnl_nlmsg_batch_start(buf, sizeof(buf));

	nftnl_mnl_batch_put(mnl_nlmsg_batch_current(batch),
			  NFNL_MSG_BATCH_BEGIN, seq++);
	mnl_nlmsg_batch_next(batch);

	nlh = nftnl_rule_nlmsg_build_hdr(mnl_nlmsg_batch_current(batch),
				NFT_MSG_DELRULE,
				family,
				NLM_F_ACK, seq++);

	nftnl_rule_nlmsg_build_payload(nlh, r);
	nftnl_rule_free(r);
	mnl_nlmsg_batch_next(batch);

	nftnl_mnl_batch_put(mnl_nlmsg_batch_current(batch), NFNL_MSG_BATCH_END,
			  seq++);
	mnl_nlmsg_batch_next(batch);

	nl = mnl_socket_open(NETLINK_NETFILTER);
	if (nl == NULL) {
		perror("mnl_socket_open");
		exit(EXIT_FAILURE);
	}

	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
		perror("mnl_socket_bind");
		exit(EXIT_FAILURE);
	}
	portid = mnl_socket_get_portid(nl);

	if (mnl_socket_sendto(nl, mnl_nlmsg_batch_head(batch),
			      mnl_nlmsg_batch_size(batch)) < 0) {
		perror("mnl_socket_send");
		exit(EXIT_FAILURE);
	}

	mnl_nlmsg_batch_stop(batch);

	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
	while (ret > 0) {
		ret = mnl_cb_run(buf, ret, 0, portid, NULL, NULL);
		if (ret <= 0)
			break;
		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
	}
	if (ret == -1) {
		perror("error");
		exit(EXIT_FAILURE);
	}
	mnl_socket_close(nl);

	return EXIT_SUCCESS;
}